1. Field of the Invention
The invention relates to hypodermic syringes and, more particularly, to a protective enclosure assembly in which the hypodermic needle is automatically, positively but releasably retained in a retracted position.
2. Prior Art
Needle protectors are well known and have been in use for many years for needles used with hypodermic syringes. Conventionally, needles are made with hubs and sockets adapted to be attached to the reduced end of a syringe. A molded plastic cap is removably secured to the hub of the needle. After mounting the needle on the syringe, the cap is removed to expose the needle for use. Following use the protective cap is replaced to prevent needle sticks during disposal.
Accidental needle stick injuries are extremely common among nurses, physicians, laboratory workers, dentists and other health care workers. Such injuries frequently occur during recapping of a needle after use or when a syringe is left on a work surface with needle exposed.
Transmission of hepatitis, the acquired immune deficiency syndrome (AIDS) and other contagious diseases can result from inadvertent needle sticks with contaminated needles.
A plethora of prior art discloses diverse needle protective devices which replace or supplement the conventional sheath with resilient devices which are biased or hand manipulated to enclose the needle following its use. Springs, bellows and inherently resilient material are employed to provide the biasing force. Examples are the following U.S. Pats.:
White No. 2,876,770 Mar 10, 1959 Spring biased PA1 Vaillancourt No. 4,725,267 Feb. 16, 1988 Bellows/manual PA1 Schwartz No. 4,775,369 Oct. 4, 1988 Inherent resiliency
All of the above mentioned projective shields are relatively complex additions to the conventional shield and are discarded along with the disposable needles. Such devices are expensive. They also can interfere with the view of the area to be injected and none are positively retained in the needle shielding position. All of the known prior art automatically actuated shields are of flexible material which may permit inadvertent contact with the needle.